1. Field of the Invention
This invention relates to improvements in techniques for residential construction and, more particularly, to the fabrication on site of metal stairways for residences which are constructed of readily available standard building components.
2. Description of Related Art
The fabrication of stairways for residential construction has for a long time customarily involved the cutting of pieces to form the respective treads and risers and securing these in position on brackets which are nailed to wooden side panels that provide the principal support for the stairway. The treads and risers in this type of construction are also generally secured to each other to render the structure more stable and secure, and to avoid the squeaking sounds which are not infrequently encountered in wooden stairways.
Metal stairways have also been known and used for a considerable period of time, and those which have been found in prior art patents are considered to fall into one of three different categories, depending upon the types of structures which are disclosed.
U.S. Pat. Nos. 724,790 of N. Bois and 751,098 of E. Ohnstrand disclose unitary stairways which are prefabricated. The principal objective is stated in one patent to be for use in fireproof buildings, banks and the like. Such construction requires expensive manufacturing machinery and the added cost does not make the stairways attractive for use in residential construction. Their design precludes on-site fabrication.
O'Donnell in U.S. Pat. No. 2,205,859 and Hood in U.S. Pat. No. 4,004,384 disclose integral tread-and-riser combinations as well as specially constructed stringers which are prefabricated. This construction also precludes basic and complete fabrication on site.
The Scherbner U.S. Pat. No. 847,699 discloses a metal staircase having wooden treads. The staircase includes metal tread supports and risers which are integrally formed by pairs and fastened together and to the metal stringers or side pieces by bolts or rivets. Likewise, the U.S. Pat. Nos. 1,219,614 of Woodbridge, 1,343,739 of Nesdall, 1,385,209 of Hall and 2,193,146 of Skeel et al all disclose stairway structures comprising integrally formed sets of treads and risers which involve special shaping of the sheet metal employed to form the respective combinations. This type of construction calls for prefabrication with relatively complex and expensive machinery and precludes construction of basic elements at the site.
The MacDonald U.S. Pat. No. 2,015,945 and the Steiber U.S. Pat. No. 919,789 disclose metal stairways formed of side stringers with separate treads and risers. However, these separate elements are still constructed of specially fabricated members. For example, MacDonald discloses treads having a bull-nose front portion including a downwardly depending flange for attachment to the adjacent riser. Similarly, Steiber discloses treads including corrugated longitudinal ribs or gutters which are pressed into the material for stiffening and ornamentation.
Fabrication of these elements requires special machinery which adds to the expense of the components and the overall stairway.